package org.bouncycastle.asn1;

import java.io.IOException;

/**
 * DER BMPString object.
 */
public class DERBMPString extends ASN1Object implements DERString {
    String string;

    /**
     * return a BMP String from the given object.
     * 
     * @param obj
     *            the object we want converted.
     * @exception IllegalArgumentException
     *                if the object cannot be converted.
     */
    public static DERBMPString getInstance(Object obj) {
        if (obj == null || obj instanceof DERBMPString) {
            return (DERBMPString) obj;
        }

        throw new IllegalArgumentException("illegal object in getInstance: "
                + obj.getClass().getName());
    }

    /**
     * return a BMP String from a tagged object.
     * 
     * @param obj
     *            the tagged object holding the object we want
     * @param explicit
     *            true if the object is meant to be explicitly tagged false
     *            otherwise.
     * @exception IllegalArgumentException
     *                if the tagged object cannot be converted.
     */
    public static DERBMPString getInstance(ASN1TaggedObject obj,
            boolean explicit) {
        DERObject o = obj.getObject();

        if (explicit || o instanceof DERBMPString) {
            return getInstance(o);
        } else {
            return new DERBMPString(ASN1OctetString.getInstance(o).getOctets());
        }
    }

    /**
     * basic constructor - byte encoded string.
     */
    public DERBMPString(byte[] string) {
        char[] cs = new char[string.length / 2];

        for (int i = 0; i != cs.length; i++) {
            cs[i] = (char) ((string[2 * i] << 8) | (string[2 * i + 1] & 0xff));
        }

        this.string = new String(cs);
    }

    /**
     * basic constructor
     */
    public DERBMPString(String string) {
        this.string = string;
    }

    public String getString() {
        return string;
    }

    public String toString() {
        return string;
    }

    public int hashCode() {
        return this.getString().hashCode();
    }

    protected boolean asn1Equals(DERObject o) {
        if (!(o instanceof DERBMPString)) {
            return false;
        }

        DERBMPString s = (DERBMPString) o;

        return this.getString().equals(s.getString());
    }

    void encode(DEROutputStream out) throws IOException {
        char[] c = string.toCharArray();
        byte[] b = new byte[c.length * 2];

        for (int i = 0; i != c.length; i++) {
            b[2 * i] = (byte) (c[i] >> 8);
            b[2 * i + 1] = (byte) c[i];
        }

        out.writeEncoded(BMP_STRING, b);
    }
}
